1. Field of the Technology
The technology presented herein relates to a motion determining apparatus and a storage medium having a motion determining program stored thereon, and more particularly to a motion determining apparatus for determining a motion of an input device including an acceleration sensor and a storage medium having a motion determining program for determining the same stored thereon.
2. Description of the Background Art
Conventionally, apparatuses have been developed for determining a motion of an input device operated by a user. The input device includes an acceleration sensor, and the motion of the input device is determined using an output from the acceleration sensor. For example, Japanese Laid-Open Patent Publication No. 2002-153673 (hereinafter, referred to as “patent document 1”) discloses a game apparatus including a game controller which is formed like a boxing glove and has a triaxial acceleration sensor. With the game apparatus, a user can enjoy a game using an output from the triaxial acceleration sensor.
The controller (glove) disclosed by patent document 1 includes a triaxial acceleration sensor having a sensor X, a sensor Y and a sensor Z. When a drastically large value is input to the sensor Y, the game apparatus traces back an output waveform obtained from the sensor Y and sets a time around value 0 as time t0. A time at which value 0 or the vicinity thereof is obtained after the output waveform shows a drastically small value is set as time t1. An acceleration detected between time t0 and time t1 is extracted from an output waveform from each of the sensors X and Z. Using the output waveform of each component, the game apparatus determines the type of the punch (for example, straight, hook, uppercut, etc.). Specifically, in the case where the output waveform from the sensor X shows a slightly positive value and the output waveform from the sensor Z does not change, the game apparatus determines that the player has given a straight punch. In the case where the output waveform from the sensor X shows a negative value at the start of operation and then shows a positive value and the waveform from the sensor Z does not change, the game apparatus determines that the player has given a hook. In the case where the waveform from the sensor X is infinite and the waveform from the sensor Z shows a large negative value and then shows a positive value, the game apparatus determines that the player has given an uppercut.
The game apparatus disclosed by patent document 1 determines the type of the punch in association with the waveform from each of the sensors X and Z, using the motion of each sensor in an acceleration detection direction as the reference for motion determination. Namely, the determination on the type of the punch depends on the direction (posture) of the glove (controller). Accordingly, when the direction of the glove worn by the player is changed, the game apparatus cannot make an accurate determination. For example, when the player wears the glove upside down or with right and left reversed, an identical punch given by the player cannot be determined as being identical. Namely, the determination on the type of the punch is significantly influenced by the posture of the glove. In addition, a game controller generally has a shape which does not look different even when held upside down by the player's hand. When such a controller includes a triaxial acceleration sensor, the above-described problem becomes more conspicuous. Therefore, the player needs to play with a very low degree of freedom in terms of direction in which the player holds the controller (posture of the controller) in order to have his punch accurately determined.